The present invention relates to an IC card and its portable terminal, and more particularly to an IC card with less power consumption and a portable terminal capable of controlling the power consumption of the IC card.
The data transfer sequence between a conventional IC card and an external equipment is as follows. Namely, an IC card is loaded into external equipment including a host computer, IC card reader, and terminal equipment (hereinafter these external equipment are collectively called a terminal). A command sent from the terminal is decoded in accordance with an internal control program of the IC card. In accordance with the decoded contents, the memory is accessed for data write, read, or erase operations. The accessed results are sent back to the terminal as a response to the command. In such operations, the terminal is always a master, whereas the IC card is a slave which waits for a command from the terminal.
Such a conventional IC card has a power consumption of about 50 mW for the one chip IC built-in type and about 210 mW for the two chip IC built-in type. This power consumption is relatively large as compared with that of a portable calculator which consumes about 0.3 to 15 mW.
Recently, an IC card-is required to have various functions for allowing various applications such as banks, hospitals, credits and the like. In order to satisfy various requirements, an IC card has now been used while loading it to a portable terminal.